CVE-2026-90203

HIGHPre-NVD 7.17.1—
EchelonGraph scoreHIGH confidence

Score 7.1 from GitHub Security Advisory (severity: HIGH) published 2026-09-17. A secondary CVSS source baseline 7.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
7.1EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 7.1Exploit: None knownExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

In the Linux kernel, the following vulnerability has been resolved:

Squashfs: check block offset is not negative

If a negative offset is read off disk (for example the offset into the decompressed fragment block), this will cause squashfs_copy_data() to perform an out of bounds access.

Fix by checking if offset is negative, and returning 0. This matches existing behaviour where an offset beyond the block returns 0 bytes copied.

To trigger this out of bounds access requires a crafted Squashfs filesystem and CAP_SYS_ADMIN to mount it. Unprivileged users will not be able to mount such a filesystem, but once mounted, an unprivileged user can trigger the out of bounds access by reading the crafted file with the negative offset.

CVSS v3
7.1
EG Score
7.1HIGHhigh confidence
EG Risk
37
EG Risk 37/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity71% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.2%
EPSS %ILE
6th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 17, 2026

Last Modified

September 18, 2026

Advisory Details (8)

Auto-updated Sep 18, 2026
No patch confirmed yet.
generic

Squashfs: check block offset is not negative - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe
generic

Squashfs: check block offset is not negative - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e300eb5002925b29be803d2661af07266cfa267e
generic

Squashfs: check block offset is not negative - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d0a3729d464fcf516416a41cf304c0c92126ee03
generic

Squashfs: check block offset is not negative - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c2a126fca820ae74872da28de68dc74d4595dc4b
generic

Squashfs: check block offset is not negative - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bbb2218eb072b0a15dc063929200183bd23c2344
generic

Squashfs: check block offset is not negative - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b169185d5c672b989985c6c2e38cafab2548ba88
generic

Squashfs: check block offset is not negative - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/95dadf366c117dcdca78a570e6832071deab1ecd
generic

Squashfs: check block offset is not negative - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3d2f0cb66c909ea2312cdef465165bb9a3ba2d84

Vendor Advisories for CVE-2026-90203(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(4 across 3 ecosystems)
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 7.2~rc7-1~exp1 (360 versions)
  • every version on: no fix on record
—
linux-6.126.12.100-1~deb12u1, 6.12.101-1~deb12u1, 6.12.107-1~deb12u1
  • every version up to 6.12.111-1~deb12u1: fixed in 6.12.111-1~deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 6.12.96-1 (35 versions)
  • every version up to 6.12.111-1: fixed in 6.12.111-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.2~rc7-1~exp1 (179 versions)
  • every version up to 7.2.6-1: fixed in 7.2.6-1
—

Data Freshness Timeline

(refreshed 28× in last 7d / 74× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-05 04:26 UTCEG score recompute
  2. 2026-10-05 04:26 UTCGHSA enrichment
  3. 2026-10-04 23:22 UTCEPSS rescore
  4. 2026-10-04 17:14 UTCGHSA enrichment
  5. 2026-10-04 06:01 UTCGHSA enrichment
  6. 2026-10-03 18:49 UTCEG score recompute
  7. 2026-10-03 18:49 UTCGHSA enrichment
  8. 2026-10-03 07:23 UTCGHSA enrichment
  9. 2026-10-02 20:11 UTCEG score recompute
  10. 2026-10-02 20:11 UTCGHSA enrichment
  11. 2026-10-02 08:58 UTCGHSA enrichment
  12. 2026-10-01 21:41 UTCEG score recompute
  13. 2026-10-01 21:41 UTCGHSA enrichment
  14. 2026-10-01 19:51 UTCEPSS rescore
  15. 2026-10-01 10:26 UTCGHSA enrichment
  16. 2026-09-30 23:15 UTCEG score recompute
  17. 2026-09-30 23:14 UTCGHSA enrichment
  18. 2026-09-30 15:04 UTCEPSS rescore
  19. 2026-09-30 11:56 UTCGHSA enrichment
  20. 2026-09-30 00:44 UTCEG score recompute
  21. 2026-09-30 00:44 UTCGHSA enrichment
  22. 2026-09-29 13:00 UTCGHSA enrichment
  23. 2026-09-29 01:46 UTCEG score recompute
  24. 2026-09-29 01:46 UTCGHSA enrichment
  25. 2026-09-28 14:35 UTCEG score recompute
Show 49 more
  1. 2026-09-28 14:35 UTCGHSA enrichment
  2. 2026-09-28 13:52 UTCEPSS rescore
  3. 2026-09-28 13:52 UTCEPSS rescore
  4. 2026-09-28 03:24 UTCGHSA enrichment
  5. 2026-09-27 16:13 UTCEG score recompute
  6. 2026-09-27 16:13 UTCGHSA enrichment
  7. 2026-09-27 13:49 UTCEPSS rescore
  8. 2026-09-27 05:01 UTCGHSA enrichment
  9. 2026-09-26 17:49 UTCEG score recompute
  10. 2026-09-26 17:49 UTCGHSA enrichment
  11. 2026-09-26 15:59 UTCEPSS rescore
  12. 2026-09-26 06:33 UTCEG score recompute
  13. 2026-09-26 06:33 UTCGHSA enrichment
  14. 2026-09-25 19:19 UTCGHSA enrichment
  15. 2026-09-25 07:22 UTCGHSA enrichment
  16. 2026-09-24 20:11 UTCEG score recompute
  17. 2026-09-24 20:11 UTCGHSA enrichment
  18. 2026-09-24 14:04 UTCEPSS rescore
  19. 2026-09-24 09:00 UTCGHSA enrichment
  20. 2026-09-23 21:49 UTCEG score recompute
  21. 2026-09-23 21:49 UTCGHSA enrichment
  22. 2026-09-23 17:54 UTCEPSS rescore
  23. 2026-09-23 10:37 UTCGHSA enrichment
  24. 2026-09-22 23:24 UTCEG score recompute
  25. 2026-09-22 23:23 UTCGHSA enrichment
  26. 2026-09-22 16:01 UTCEPSS rescore
  27. 2026-09-22 12:08 UTCGHSA enrichment
  28. 2026-09-22 00:56 UTCEG score recompute
  29. 2026-09-22 00:55 UTCGHSA enrichment
  30. 2026-09-21 21:09 UTCEPSS rescore
  31. 2026-09-21 13:44 UTCGHSA enrichment
  32. 2026-09-21 02:33 UTCEG score recompute
  33. 2026-09-21 02:33 UTCGHSA enrichment
  34. 2026-09-20 20:16 UTCEPSS rescore
  35. 2026-09-20 15:21 UTCGHSA enrichment
  36. 2026-09-20 04:08 UTCGHSA enrichment
  37. 2026-09-19 16:56 UTCEG score recompute
  38. 2026-09-19 16:56 UTCGHSA enrichment
  39. 2026-09-19 05:43 UTCEG score recompute
  40. 2026-09-19 05:43 UTCGHSA enrichment
  41. 2026-09-18 19:28 UTCEPSS rescore
  42. 2026-09-18 18:31 UTCEG score recompute
  43. 2026-09-18 18:31 UTCGHSA enrichment
  44. 2026-09-18 18:05 UTCEG score recompute▲ 7.10
  45. 2026-09-18 18:04 UTCGHSA enrichment
  46. 2026-09-18 17:59 UTCMITRE cvelistV5CVSS v3 → 7.1 · severity → HIGH
  47. 2026-09-17 17:23 UTCNVD update
  48. 2026-09-17 16:41 UTCEG score recompute
  49. 2026-09-17 16:19 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-90203?
CVE-2026-90203 is a high vulnerability published on September 17, 2026. In the Linux kernel, the following vulnerability has been resolved: Squashfs: check block offset is not negative If a negative offset is read off disk (for example the offset into the decompressed fragment block), this will cause squashfscopydata() to perform an out of bounds access. Fix by…
When was CVE-2026-90203 disclosed?
CVE-2026-90203 was first published on September 17, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-90203 actively exploited?
CVE-2026-90203 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (6th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-90203?
CVE-2026-90203 has a CVSS base score of 7.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-90203?
No fix for CVE-2026-90203 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-90203 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-90203

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